(1). Field of the Invention
This invention relates generally to pipes having roller boxes located at bends in the pipes for aiding the movement of cables positioned within the pipes, and more particularly to a roller excitation device which is used to cause rollers housed by such roller boxes to roll or turn.
(2). Description of the Prior Art
In certain applications, there is a pipe located outboard of a vessel. This pipe has a cable located therein. Typically, the pipe has bends formed in it, and, in order to minimize the friction encountered by the cable as it passes through the pipe and negotiates the bends, roller box assemblies are positioned at these bends. FIG. 1 illustrates a vessel wall 10 with a section of pipe 12 having a pair of roller box assemblies, each generally indicated at 14, positioned at the bends of the pipe 12. As shown, a roller box assembly 14 can be positioned anywhere along the length of the pipe 12 where it bends or turns.
FIGS. 2 and 3 illustrate a single roller box assembly 14 in plan view and cross section view, respectively. As shown in FIG. 2, the roller box assembly 14 has an arcuate housing 16 and a plurality of rollers, each indicated at 18, positioned within the housing 16. Referring to FIG. 3, the housing 16 of the roller box assembly 14 has a generally U-shaped cross section. Specifically, the housing 16 has a partial tube 20 which covers the open end of the housing 16 and a plurality of roller shafts or pins 22 captured by the housing 16, each roller shaft 22 having the roller 18 mounted thereon. The rollers 18 extend perpendicularly with respect to the direction of a cable 24 located in the space defined by the partial tube 20 and the rollers 18. The arrangement is such that each roller 18 is adapted to roll upon engaging the cable 24 when moving the cable 24 linearly through pipe 12 and roller box assemblies 14. This rotation of the roller 18 upon engaging the cable 24 eases the linear motion of the cable 24 passing through the pipe 12 at the bend.
Occasionally, rollers 18 and/or roller shafts 22 become immobile or seize due to a variety of causes (e.g., lack of lubrication, foreign objects preventing rotation of the rollers, etc.). In order to ensure that the roller box assemblies 14 perform their intended function, it is necessary to both test the assemblies 14 and to identify rollers 18 that are seized. Presently, there is no way of detecting or identifying whether rollers 18 are functional or non-functional. The present invention is provided for overcoming these above-noted constraints.